# \#Lightmass **URL:** https://forums.unrealengine.com/tag/lightmass/126.md [Latest](https://forums.unrealengine.com/latest.md) · [Categories](https://forums.unrealengine.com/categories.md) · [Tags](https://forums.unrealengine.com/tags.md) --- ## [CPU Lightmass UE 5.8](https://forums.unrealengine.com/t/cpu-lightmass-ue-5-8/2729372)
**Author:** [@apfelbaum](https://forums.unrealengine.com/u/apfelbaum)\ **Replies:** 3\ **Last updated:** [August 26, 2026, 3:00pm UTC](https://forums.unrealengine.com/t/cpu-lightmass-ue-5-8/2729372 "2026-08-26T15:00:48Z")
Summary CPU Lightmass is broken. Skylight bounce is not working on static meshes as well as clear coat enabled materials dont have skylight occlusion. this affects legacy as well as substrate materials. The name of the … --- ## [Lightmass fails to build on Apple Silicon Macs in UE 5.6+ when Embree is enabled. ](https://forums.unrealengine.com/t/lightmass-fails-to-build-on-apple-silicon-macs-in-ue-5-6-when-embree-is-enabled/2736545)
**Author:** [@magnuslonngi](https://forums.unrealengine.com/u/magnuslonngi)\ **Replies:** 0\ **Last updated:** [July 18, 2026, 1:12am UTC](https://forums.unrealengine.com/t/lightmass-fails-to-build-on-apple-silicon-macs-in-ue-5-6-when-embree-is-enabled/2736545 "2026-07-18T01:12:32Z")
Summary On Apple Silicon Macs, static lighting builds consistently fail in Unreal Engine 5.6, 5.7, and 5.8 when Embree is enabled. The same project builds successfully in Unreal Engine 5.5.4. Disabling Embree by adding … --- ## [Crashes all the time with lightass scene](https://forums.unrealengine.com/t/crashes-all-the-time-with-lightass-scene/2475603)
**Author:** [@yellowborb](https://forums.unrealengine.com/u/yellowborb)\ **Replies:** 1\ **Last updated:** [June 25, 2026, 7:36pm UTC](https://forums.unrealengine.com/t/crashes-all-the-time-with-lightass-scene/2475603 "2026-06-25T19:36:56Z")
I have an issue that i saw many times in forums and no one seems to have find any solution to it. I have a very simple interior scene, with built/baked shadows and lightmaps. If i press play just after the level have be… --- ## [How can I create a pre-baked lighting room prefab in UE4?](https://forums.unrealengine.com/t/how-can-i-create-a-pre-baked-lighting-room-prefab-in-ue4/2723291)
**Author:** [@xipigta](https://forums.unrealengine.com/u/xipigta)\ **Replies:** 2\ **Last updated:** [June 10, 2026, 1:35pm UTC](https://forums.unrealengine.com/t/how-can-i-create-a-pre-baked-lighting-room-prefab-in-ue4/2723291 "2026-06-10T13:35:56Z")
I’m currently working on a very large-scale environment in UE4. The project requires a huge number of repeated interior rooms/buildings, so I would like to create reusable room prefabs that already contain baked lighting… --- ## [Movable objects turning black when using static lights](https://forums.unrealengine.com/t/movable-objects-turning-black-when-using-static-lights/2723673)
**Author:** [@Divyanshu](https://forums.unrealengine.com/u/Divyanshu)\ **Replies:** 1\ **Last updated:** [May 22, 2026, 6:38am UTC](https://forums.unrealengine.com/t/movable-objects-turning-black-when-using-static-lights/2723673 "2026-05-22T06:38:04Z")
Hello everyone, I am making a horror indoor game in which I am using static lights, but when I am placing the door actors, the frame of the door, which is assigned static, is being lit correctly, but the movable door mes… --- ## [How can I bake lighting for only a small specific area in UE5? ](https://forums.unrealengine.com/t/how-can-i-bake-lighting-for-only-a-small-specific-area-in-ue5/2721518)
**Author:** [@xipigta](https://forums.unrealengine.com/u/xipigta)\ **Replies:** 3\ **Last updated:** [May 15, 2026, 12:26pm UTC](https://forums.unrealengine.com/t/how-can-i-bake-lighting-for-only-a-small-specific-area-in-ue5/2721518 "2026-05-15T12:26:52Z")
I’m currently working on a very large-scale world in UE5, and for performance reasons I decided to use a traditional baked lighting workflow instead of Lumen. For this project, being able to bake lighting for only a sma… --- ## [GPU Lightmass baking artifact ](https://forums.unrealengine.com/t/gpu-lightmass-baking-artifact/2722108)
**Author:** [@loooooool8](https://forums.unrealengine.com/u/loooooool8)\ **Replies:** 0\ **Last updated:** [May 14, 2026, 2:35pm UTC](https://forums.unrealengine.com/t/gpu-lightmass-baking-artifact/2722108 "2026-05-14T14:35:18Z")
Hello there, I’m using 5.5.4, I have disabled Lumen and I’m baking lights using GPU Lightmass, but I keep getting artifacts on a certain part of the map, the meshes are used in other places but they don’t get the same… --- ## [Unreal (5.4.4 and 5.6 Preview) Lightmass on Mac stopping at 0%](https://forums.unrealengine.com/t/unreal-5-4-4-and-5-6-preview-lightmass-on-mac-stopping-at-0/2530543)
**Author:** [@GameAnim](https://forums.unrealengine.com/u/GameAnim)\ **Replies:** 15\ **Last updated:** [April 22, 2026, 6:41pm UTC](https://forums.unrealengine.com/t/unreal-5-4-4-and-5-6-preview-lightmass-on-mac-stopping-at-0/2530543 "2026-04-22T18:41:55Z")
I am unable to get Unreal to build lighting on an Apple MacBook Pro M4, with it stopping at 0% before failing, and offering no errors beyond: LogStaticLightingSystem: Warning: Failed to build lighting!!! Lighting build … --- ## [Lumen vs lightmass - why so different? ](https://forums.unrealengine.com/t/lumen-vs-lightmass-why-so-different/2710125)
**Author:** [@booclay](https://forums.unrealengine.com/u/booclay)\ **Replies:** 7\ **Last updated:** [March 31, 2026, 10:37am UTC](https://forums.unrealengine.com/t/lumen-vs-lightmass-why-so-different/2710125 "2026-03-31T10:37:31Z")
Why does lightmass look so bad/blue/over exposed? I’m new to Unreal, but I imported a scene using datasmith (from 3ds) into Unreal 5.7. The scene looked really good using lumen, so I thought I should set about baking th… --- ## [Stationary light source does not create static shadows (likely a bug)](https://forums.unrealengine.com/t/stationary-light-source-does-not-create-static-shadows-likely-a-bug/2706187)
**Author:** [@GrigLog](https://forums.unrealengine.com/u/GrigLog)\ **Replies:** 7\ **Last updated:** [March 15, 2026, 3:36pm UTC](https://forums.unrealengine.com/t/stationary-light-source-does-not-create-static-shadows-likely-a-bug/2706187 "2026-03-15T15:36:47Z")
The description of the Stationary type of mobility states that the shadowing of a light source with it must be baked by Lightmass: But as of 5.7.4 (the same issue was present in 5.7.3, by the way), this is not the cas… --- ## [5.7 Lightmass Issues (Crashes and Bugs)](https://forums.unrealengine.com/t/5-7-lightmass-issues-crashes-and-bugs/2694991)
**Author:** [@DanielOS96](https://forums.unrealengine.com/u/DanielOS96)\ **Replies:** 1\ **Last updated:** [March 5, 2026, 9:31pm UTC](https://forums.unrealengine.com/t/5-7-lightmass-issues-crashes-and-bugs/2694991 "2026-03-05T21:31:42Z")
Hi, if anyone know anything about baked lighting in UE5.7 I would be eternally grateful for some help. I have been having non-stop issues with lightmass and volume lighting in 5.7 it seems unusable it’s so buggy. Is it … --- ## [GPU Lightmass Error: Array index out of bounds](https://forums.unrealengine.com/t/gpu-lightmass-error-array-index-out-of-bounds/2694495)
**Author:** [@DanielOS96](https://forums.unrealengine.com/u/DanielOS96)\ **Replies:** 2\ **Last updated:** [February 12, 2026, 4:42pm UTC](https://forums.unrealengine.com/t/gpu-lightmass-error-array-index-out-of-bounds/2694495 "2026-02-12T16:42:44Z")
I’m getting the following error. I have tried clearing and validating the swarm cache I have tried enabling and disabling bForceNoPrecomuputedLighting and I have checked to make sure my ram isn’t getting maxed out. What … --- ## [How to Get GPU Lightmass Working with HLODs?](https://forums.unrealengine.com/t/how-to-get-gpu-lightmass-working-with-hlods/2695092)
**Author:** [@DanielOS96](https://forums.unrealengine.com/u/DanielOS96)\ **Replies:** 1\ **Last updated:** [January 26, 2026, 8:06pm UTC](https://forums.unrealengine.com/t/how-to-get-gpu-lightmass-working-with-hlods/2695092 "2026-01-26T20:06:09Z")
I am using UE5.7 so I am forced to use GPU lightmass instead of CPU as the CPU version ignores Lightmass Importance Volumes. With this being the case I am unable to use GPU lightmass with HLODs. It will only bake light … --- ## [Does Lightmass Important volumes actually do anything?](https://forums.unrealengine.com/t/does-lightmass-important-volumes-actually-do-anything/2694681)
**Author:** [@DanielOS96](https://forums.unrealengine.com/u/DanielOS96)\ **Replies:** 0\ **Last updated:** [January 24, 2026, 8:35pm UTC](https://forums.unrealengine.com/t/does-lightmass-important-volumes-actually-do-anything/2694681 "2026-01-24T20:35:45Z")
Do Lightmass Importance volumes actually do anything if you bake lighting with volumetric lighting? Or is this some kind of social experiment from Epic to see if we will play along and just place random boxes over cool s… --- ## [lightmass crashing](https://forums.unrealengine.com/t/lightmass-crashing/2555552)
**Author:** [@User-0befe8ef7d](https://forums.unrealengine.com/u/User-0befe8ef7d)\ **Replies:** 10\ **Last updated:** [January 3, 2026, 7:53am UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552 "2026-01-03T07:53:58Z")
i keep getting this ■■■■ crash i tried to force log and go through every line of the log but couldnt find any fix Assertion failed: TextureUniformBase \[File:D:\\build++UE5\\Sync\\Engine\\Source\\Runtime\\Engine\\Private\\Mater… --- ## [Lightmass crashes every build](https://forums.unrealengine.com/t/lightmass-crashes-every-build/342315)
**Author:** [@Entropikz](https://forums.unrealengine.com/u/Entropikz)\ **Replies:** 11\ **Last updated:** [December 20, 2025, 12:47pm UTC](https://forums.unrealengine.com/t/lightmass-crashes-every-build/342315 "2025-12-20T12:47:00Z")
Hey, I just recently started developing and am trying to become more familiar with UE4. I have been trying to use the BUILD tool as I have multiple objects inside of my map that require building. But I am consistently ge… --- ## [T.array resize error ](https://forums.unrealengine.com/t/t-array-resize-error/2678172)
**Author:** [@chris457k](https://forums.unrealengine.com/u/chris457k)\ **Replies:** 1\ **Last updated:** [November 24, 2025, 6:16pm UTC](https://forums.unrealengine.com/t/t-array-resize-error/2678172 "2025-11-24T18:16:54Z")
Project setup: Map size: nearly 5 km Environment: Imported from Fab https://www.fab.com/listings/35ca06cf-a124-44aa-b2ac-5b233223f3a2 Engine: UE 5.5 (no major changes to the environment after import) Scalabi… --- ## [UE5 - VirtualTextureAllocator crash when building lighting with GPULightmass](https://forums.unrealengine.com/t/ue5-virtualtextureallocator-crash-when-building-lighting-with-gpulightmass/528258)
**Author:** [@Ozykz](https://forums.unrealengine.com/u/Ozykz)\ **Replies:** 7\ **Last updated:** [November 7, 2025, 12:51pm UTC](https://forums.unrealengine.com/t/ue5-virtualtextureallocator-crash-when-building-lighting-with-gpulightmass/528258 "2025-11-07T12:51:14Z")
I am getting the following error in UE5 when trying to build lighting: Ensure condition failed: Index \<= 0x8000 \[File:D:\\build++UE5\\Sync\\Engine\\Source\\Runtime\\Renderer\\Private\\VT\\VirtualTextureAllocator.cpp\] \[Line: 113\] … --- ## [Add Swarm Agent back to UE5.6](https://forums.unrealengine.com/t/add-swarm-agent-back-to-ue5-6/2634718)
**Author:** [@jkinz3](https://forums.unrealengine.com/u/jkinz3)\ **Replies:** 0\ **Last updated:** [August 8, 2025, 11:56am UTC](https://forums.unrealengine.com/t/add-swarm-agent-back-to-ue5-6/2634718 "2025-08-08T11:56:06Z")
I haven’t seen any epic devs comment on this but Swarm Agent is missing from 5.6 and the only way to utilize static lighting is to download a previous version and copy/paste the exe into 5.6. Since Epic isn’t deprecating… --- ## [Tutorial: Fix GPU Lightmass Crashes in Unreal Engine 5 – Find Problematic Assets Automatically!](https://forums.unrealengine.com/t/tutorial-fix-gpu-lightmass-crashes-in-unreal-engine-5-find-problematic-assets-automatically/2590751)
**Author:** [@LarsH](https://forums.unrealengine.com/u/LarsH)\ **Replies:** 0\ **Last updated:** [July 4, 2025, 7:51pm UTC](https://forums.unrealengine.com/t/tutorial-fix-gpu-lightmass-crashes-in-unreal-engine-5-find-problematic-assets-automatically/2590751 "2025-07-04T19:51:00Z")
GPU Lightmass Watchdog – Automatically Detect Crashing Assets During Lightmap Baking I’ve created a tool and video tutorial to help track down assets that cause crashes during GPU Lightmass warm-up in Unreal Engine 5. T… --- ## [GPU Lightmass Point Light - Source Radius](https://forums.unrealengine.com/t/gpu-lightmass-point-light-source-radius/2519524)
**Author:** [@rlopezll](https://forums.unrealengine.com/u/rlopezll)\ **Replies:** 0\ **Last updated:** [May 20, 2025, 10:46am UTC](https://forums.unrealengine.com/t/gpu-lightmass-point-light-source-radius/2519524 "2025-05-20T10:46:53Z")
Hi, I have a problem with a point light that uses a Source Radius when generating lightmaps with the GPU Lightmass plugin. Here you can see the difference between CPU and GPU lightmap generation: GPU Lightmass: CPU … --- ## [GPU Lightmass support for RX7000/RDNA3 GPU's](https://forums.unrealengine.com/t/gpu-lightmass-support-for-rx7000-rdna3-gpus/2450307)
**Author:** [@stormergames001](https://forums.unrealengine.com/u/stormergames001)\ **Replies:** 0\ **Last updated:** [April 10, 2025, 9:33pm UTC](https://forums.unrealengine.com/t/gpu-lightmass-support-for-rx7000-rdna3-gpus/2450307 "2025-04-10T21:33:22Z")
My question is simple, what are the known issues/compatibility for GPU lightmass lightmap baking with AMD RX7000/RDNA3 GPU’s? I am using an RX 7900 XTX and I have had zero success with baking light maps through GPU light… --- ## [Moving Sub-Level Location does not also move Baked Lighting with it.](https://forums.unrealengine.com/t/moving-sub-level-location-does-not-also-move-baked-lighting-with-it/417882)
**Author:** [@Shadow\_Knights](https://forums.unrealengine.com/u/Shadow_Knights)\ **Replies:** 14\ **Last updated:** [February 16, 2025, 7:49am UTC](https://forums.unrealengine.com/t/moving-sub-level-location-does-not-also-move-baked-lighting-with-it/417882 "2025-02-16T07:49:25Z")
Hello, I have what appears to be a bug with regards to Baked Lighting information not moving with Sub Levels in the Persistent Level. This causes each SubLevel to have incorrect lighting information on the terrain/room… --- ## [Swarm agent connection issues](https://forums.unrealengine.com/t/swarm-agent-connection-issues/474564)
**Author:** [@TheBatWithTheHat](https://forums.unrealengine.com/u/TheBatWithTheHat)\ **Replies:** 1\ **Last updated:** [January 22, 2025, 8:32pm UTC](https://forums.unrealengine.com/t/swarm-agent-connection-issues/474564 "2025-01-22T20:32:06Z")
Hi All, we are having some issues with using swarm. Basically what we are getting is that is distributing on the local machine that is running the lightmass build and it shows this message on the agent of any remote ma… --- ## [Unreal lightMass Broken on UE 5.1, 5.2 and 5.3 on M1 Mac?](https://forums.unrealengine.com/t/unreal-lightmass-broken-on-ue-5-1-5-2-and-5-3-on-m1-mac/811563)
**Author:** [@EmmadIlyas](https://forums.unrealengine.com/u/EmmadIlyas)\ **Replies:** 5\ **Last updated:** [January 15, 2025, 9:13am UTC](https://forums.unrealengine.com/t/unreal-lightmass-broken-on-ue-5-1-5-2-and-5-3-on-m1-mac/811563 "2025-01-15T09:13:36Z")
A few Days ago the Unreal Lightmass Failed on my UE 5.2 Build, I cloned and Built the latest 5.3 from code but I’m still receiving this message when I try to build the lighting --- ## [No working lighting in HTML5/Mobile](https://forums.unrealengine.com/t/no-working-lighting-in-html5-mobile/315224)
**Author:** [@anonymous\_user\_c2bbafad1](https://forums.unrealengine.com/u/anonymous_user_c2bbafad1)\ **Replies:** 0\ **Last updated:** [April 16, 2015, 8:24am UTC](https://forums.unrealengine.com/t/no-working-lighting-in-html5-mobile/315224 "2015-04-16T08:24:05Z")
Hi all, So, I’ve been working on a HTML5 demo of a project I’ve been doing, however I can’t seem to get any lights to actually show. Currently, I have gone through all the documentation regarding mobile lighting and tr… --- ## [Black artefacts with GPU Lightmass on large meshes](https://forums.unrealengine.com/t/black-artefacts-with-gpu-lightmass-on-large-meshes/2261200)
**Author:** [@automatic4ppl](https://forums.unrealengine.com/u/automatic4ppl)\ **Replies:** 0\ **Last updated:** [January 5, 2025, 5:47pm UTC](https://forums.unrealengine.com/t/black-artefacts-with-gpu-lightmass-on-large-meshes/2261200 "2025-01-05T17:47:51Z")
Hi everybody, hope you’re all doing great! As per thread subject I’m stumbling upon a weird visual artifact were my meshes are covered by weird dark stains only when lit by Static Lights. I’m baking lights using GPU Li… --- ## [Lightmap from previous versions not being loaded in 5.5.1](https://forums.unrealengine.com/t/lightmap-from-previous-versions-not-being-loaded-in-5-5-1/2240423)
**Author:** [@RotemShi](https://forums.unrealengine.com/u/RotemShi)\ **Replies:** 0\ **Last updated:** [December 24, 2024, 3:26pm UTC](https://forums.unrealengine.com/t/lightmap-from-previous-versions-not-being-loaded-in-5-5-1/2240423 "2024-12-24T15:26:54Z")
It seems that the lightmap for any project in which lighting was built before 5.5 can not be loaded in 5.5, and lighting needs to be rebuilt in the 5.5 editor. Recreation: Create an empty project in 5.4.4 In a fully e… --- ## [Why does my baked lighting look so flat?](https://forums.unrealengine.com/t/why-does-my-baked-lighting-look-so-flat/2154335)
**Author:** [@roberteker](https://forums.unrealengine.com/u/roberteker)\ **Replies:** 3\ **Last updated:** [November 27, 2024, 1:45pm UTC](https://forums.unrealengine.com/t/why-does-my-baked-lighting-look-so-flat/2154335 "2024-11-27T13:45:08Z")
This is already baked with production quality, but it feels as if it’s basically on or off, so ambiance at all… anyone know why? Is it the HDRIBackdrop plug-in which breaks things or? --- ## [Access static lighting information from c++](https://forums.unrealengine.com/t/access-static-lighting-information-from-c/404631)
**Author:** [@Bellian](https://forums.unrealengine.com/u/Bellian)\ **Replies:** 1\ **Last updated:** [November 26, 2024, 8:46am UTC](https://forums.unrealengine.com/t/access-static-lighting-information-from-c/404631 "2024-11-26T08:46:44Z")
Hi, I want to know if it is possible to access the static lighting information of a StaticMeshComponent in the scene. The idea was to try to detect completely occluded objects by evaluating the computed lighting inform… [Next page](https://forums.unrealengine.com/tag/lightmass/126.md?match_all_tags=true&page=1&tags%5B%5D=Lightmass)